The present invention relates to a computer system, and more particularly to an art of a computer system that can rewrite a boot process program (referred to as a BOOT process program, hereinafter) in service by remote control.
Conventionally, in a computer system of that type, rewriting the content of a boot process program is generally made by first opening the cabinet of the computer system and then replacing the ROM to which the BOOT process program is written.
FIG. 6 illustrates the configuration of a conventional computer system. Referring to FIG. 6, a conventional computer system includes a bus 1 necessary for operation of the computer system, a CPU 2, a secondary storage unit 8, a multitasking operation system (OS) 9 stored on the secondary storage unit 8, a RAM 5, and a ROM 13 such as a UVEPROM (Ultra-Violet Erasable Programmable ROM) or mask ROM 13.
FIG. 7 is a flowchart showing the sequence ranging from a system start-up to re-operation after replacement with the ROM 13 in the conventional computer system.
Referring to FIGS. 6 and 7, first, the computer system starts up according to a BOOT process program written in the ROM 13 (step 202). Thereafter, the multitasking OS 9 stored in the secondary storage unit 8 is loaded onto the RAM 5 and started up (step 204). In the following steps, the computer system executes in normal working conditions (step 206).
To rewrite the BOOT process program, the cabinet of the computer system is opened (step 210) after shutdown of the computer system (step 208). Then, the ROM 13 mounted for BOOT operation is replaced by a ROM in which a new BOOT process program is written (step 212).
The cabinet of the computer system is closed (step 214). Then, the computer system is started up using the BOOT process program written in the new ROM 13 (step 216). Thereafter, the multitasking OS 9 stored on the secondary storage unit 8 is loaded onto the ROM 5 and restarted (step 218). In the following steps, the computer system executes processes in normal working conditions (step 220).
In another method of rewriting the content of a BOOT process program in that type of computer, JP-A-324857/1994, for example, proposes that a rewritable non-volatile memory device is used for the BOOT process program. This method, however, requires to carry the secondary storage medium such as a rewrite processing memory device or flexible disk to the site where the computer system exists. Hence, the BOOT process program must be rewritten only at the place where the computer system exists.
JP-A-259242/1994, for example, proposes a method that a BOOT process program written in a non-volatile memory device can be corrected while it is incorporated in a unit. However, this method cannot amend the BOOT process program if rewrite information is previously stored into the secondary storage medium in the computer system.
Any one of the foregoing prior arts has the problem that a maintenance crew must go to the site where the computer system exists and operate the computer system to rewrite the BOOT process program.
The reason is that BOOT process program rewrite information cannot be supplied if it is not loaded to the computer system. For example, in the prior art shown in FIG. 6, the cabinet of the computer system must be opened to exchange the ROM for a new one. In the prior art disclosed in JP-A-324857/1994, a secondary storage medium such as a memory device or flexible disk must be mounted. Furthermore, the prior art disclosed in JP-A-259242/1994 can remotely execute the rewrite operation, but a maintenance crew must go to the site where the computer system exists to rewrite previous rewrite information into the secondary storage medium.